factory 487 #1 Posted January 24, 2015 Does anyone know the correct thickness of the original cylinder O rings? I have a box of assorted O rings but the larger diameter ones seem to be too thick and the cylinder won't screw down far enough to allow the starter cover to fit. David Share this post Link to post Share on other sites
Webhead 95 #2 Posted January 25, 2015 I'm getting .114. but my mic might be crushing it a bit. I have these if you need one. Share this post Link to post Share on other sites
factory 487 #3 Posted January 25, 2015 Thanks for measuring an original, the ones I have are about .105". It's for the early engine from the Petro pump, the part no (33-2) used is the same from 1962 to 1972, maybe my home-made exhaust gaskets are slightly too thick, or perhaps the modern O rings don't crush enough. O rings are available in lots of different thickness on ebay, should I try some slightly smaller? David Share this post Link to post Share on other sites
Wallfish 698 #4 Posted January 29, 2015 Seems like it must be a combination of things but I believe that cylinder needs to screw all the way in. If not, the piston can't reach the top for the best compression. Share this post Link to post Share on other sites
factory 487 #5 Posted January 31, 2015 The cylinder was all the way in before I started the repair of this engine, as can be seen in this picture. This is as far as I can get the cylinder with the .105" O-ring, the gaskets were made from Klingersil C-4324 1/32" that I bought at a local engine show last year. I bought some O-rings the next size down at .079" (2mm) earlier this week, I managed to get the cylinder all the way down, but the cylinder tool T-bar got bent in the process. The engine will have to be stripped down again though, as it has lost spark. This is due to me fitting a later aluminium flywheel key when I replaced the flywheel with a later one. The flywheel must have turned when tightened. The key slot is deeper than the later crankshaft & the damaged key is now stuck. David Share this post Link to post Share on other sites
Webhead 95 #6 Posted January 31, 2015 These little suckers can be very frustrating to work on. I can attest to banging my head on the wall a few times, and I bet Wallfish would say the same! Share this post Link to post Share on other sites
factory 487 #7 Posted January 31, 2015 I had to remove the crankshaft to remove the damaged key, These early engines aren't as bad to strip down as the later ones though, the bearings don't escape as easily. I will need to made to a custom flywheel key for this engine, as it needs one smaller than the original but bigger than the later one. David Share this post Link to post Share on other sites
Webhead 95 #8 Posted January 31, 2015 As I once read from an old dude that used to work at a shop that serviced O&Rs- "Anytime an O&R came in to the shop for repair, everybody would disappear!" Share this post Link to post Share on other sites
Wallfish 698 #9 Posted January 31, 2015 That sucks about the key. I never paid much attention to those crank and key differences and never even noticed they were different. Share this post Link to post Share on other sites
